Finding ancient petroglyphs in the mountains of Kyrgyzstan

For thousands of years, humankind has left its mark on the global landscape in the form of petroglyphs—images etched into rocky outcrops, initially with stone tools and later metal instruments. Often carved over the course of several millennia at a singular locale, these ancient markings attest their historical relevance over time. And thus, petroglyph sites can be understood as sacred open-air “history books” rendered in stone.

In this context, petroglyphs are an important complement to archaeological data gleaned from burial sites. In broad terms, petroglyphs tend to provide insight into burial rites, social norms and material culture. They tell us about life events and the mythical ideas associated with them.

While petroglyphs are found on all five continents, the mountainous areas of Central Asia, southern Siberia and western Mongolia are especially rich in sites dating from the Bronze Age, the Iron Age and the Turkic Period. Within this expanse of petroglyphs, the site of Saimaluu Tash in Kyrgyzstan is one of the largest and highest. It lies in the eastern part of the expansive Fergana Mountain Range, some 115 kilometres northeast of the city of Osh.

Due to Saimaluu Tash elevation, which ranges from 2,860 to 3,350 metres, the site is covered by snow 11 months of the year and is only accessible from mid-July to mid-August. In 2017, Esri, a global market leader in Geographic Information System (GIS) technology, helped a mixed team of local and international scientists to overcome the challenges and assisted with their research. Hexagon Geosystems supported their efforts providing the latest GNSS technology.

“Hexagon Geosystems’ technology facilitated the data collection, its high-level of accuracy, efficiency and precision exceeded our expectations for this demanding project,” said Matthias Schenker, CTO at Esri Switzerland. “The direct support for the Leica GG04 Smart Antenna in Collector for ArcGIS made it really easy for us to directly integrate the data collection in our workflow.”

Rediscovering history

The military topographer Nikolai G. Kludov officially re-discovered Saimaluu Tash—meaning “stones with drawings” in the Kyrgyz language—in 1902. However, more than four decades would pass before SM. Zima and Alexander N. Bernshtam conducted campaigns there, in 1946 and 1950, respectively. In the decades since those initial forays to the site, sporadic fieldwork was conducted up until the early 2000s.

The objective of the researchers’ most recent expedition was to thoroughly survey, photograph and map the site with a view to produce a monograph and 3D interactive maps.

Expedition participants included:

Three archaeologists and petroglyph experts

Two GIS specialists

A local ground support team.

Their goal was to establish thematic clusters of petroglyphs within certain spaces. Furthermore, the team hoped to identify what appeared to be traces of as many as nine ancient settlements and burial sites on satellite imagery with 50 centimetres of resolution.

The expedition

The petroglyphs are concentrated in two valleys, divided by a steep ridge in the Saimaluu Tash Mountain Range—at the relatively large site Saimaluu Tash I in the western valley and at the smaller, and slightly more recent, site of Saimaluu Tash II in the neighbouring eastern valley. Saimaluu Tash I covers some 1.3 square kilometres while Saimaluu Tash II Covers less than 1 km2.

Over the course of three weeks, the team surveyed a total of around 4,500 stones with petroglyphs and between 25,000 to 30,000 single images. The location of each of the petroglyph bearing stones was surveyed using Leica Geosystems GNSS receivers with decimetre accuracy in combination with the Collector for ArcGIS application on mobile devices. The application was configured to allow offline data collection on the basis of a high-resolution satellite image of the area for more timely and informed decisions.

“The Leica Zeno GG04 Smart Antenna was a unique tool for our project considering the demanding environmental conditions of the valley,” said Schenker. “Given its high precision technology, we were able to accomplish our goal and gather the most accurate data.”

The orientation (azimuth) was recorded for each petroglyph, together with a photograph and description of it. A digital elevation model (DEM) and orthorectified imagery of the study area were created from aerial photographs taken by an unmanned aerial vehicle (UAV). The Leica GG04 GNSS Smart Antenna was also used to survey ground control points (GCPs) to improve the horizontal and vertical location accuracy of the DEM and orthophotos. The data were then categorised and stored in a geo-database in order to analyse the spatial distribution of the petroglyphs within the site as a whole as well as of individual categories. The results are best visualised on interactive 2D and 3D applications.

For spatial and statistical analysis, the data was categorised and stored in a geodatabase and evaluated using ArcGIS Pro by Esri. This allowed analysis of the spatial distribution of the petroglyphs within the site as a whole as well as of individual classes of petroglyphs.

From this dataset, various information products are generated as results, in the form of interactive 2D and 3D web applications, as well as in the form of traditional paper maps showing the location and categorisation of the petroglyphs. The web-based maps and applications will be made available via ArcGIS Online and can be used for filtering and further analysis.

Additionally, the data will also be made available for use in the AuGeo app created by Esri Labs. This allows to use this data in an augmented reality (AR) environment.

Revolutionising archaeology

“Archaeologists embrace technology, adopt new tools and accept revolutionary techniques that transform archaeology like never before in the past,” said Schenker. “We are delighted to be part of this transformation.”

The petroglyphs at Saimaluu Tash represent a time span of almost 3,000 years and reflect a great variety of themes. Since their creators selected motifs from their own surroundings and economies, which in turn were determined by climatic conditions, it is possible to establish a correlation between the petroglyphs, the climate, and the local economy. By revealing of such information of the past we gain a better understanding of the historical context and our social development over the years.

All information about the Saimaluu Tash petroglyph area is derived from the official expedition report by Christoph Baumer, a Swiss scholar and explorer, as it was published in the Fall 2017 edition of “The Explorers Journal”.